Anxious and can't shake it

So, this week, I was offered a TOC job for three half-days per week for ten weeks. That would be Tues, Wed, Thurs where I would be doing the same thing, at the same school, in the same classrooms each day. Very exciting idea. BUT, the only problem is that I get paid the same amount, as a TOC, for the morning (8:30 - 12:20) as for the afternoon (1:05 - 2:30). Also, TOCs hardly ever get called in for just the afternoon, because, hey, it's only an hour and a bit. Anyhow, I have never been called in for only an afternoon, but I have gotten calls for morning only. If I were to take the position, I would be committed to it for ten weeks. That means, ten weeks where I would not have a chance to get any longer term placements and no contracts.

So... I declined it, sadly. We need money! I can't afford to limit myself to three days where I probably won't make that extra money, and I lose the possibility of longer term assignments.

The only problem is that, now, I feel sick about it. I feel like I closed a door that was in front of me without even testing the knob. But... I wouldn't want to "try it out for a while" because that is unfair to the school! That leaves them without someone that is consistent and committed. And, if I were the principal, I would want someone who is both! I just feel terrible. I know that I have been blessed with work because I worked 7.5 out of the first 9 days back... But, now, I have only worked .5 days out of 2 and now I am getting nervous that I am not going to be called in and I should have taken that job because then I would, at least, be guaranteed some income every week, even if it is 270 bucks less than what I could make (if I were to get called in for full days on those three days).
I can't shake this feeling in the pit of my stomach... Brutal!
Enough about that... think about the crazy kid...